Method and device for complex forming a metal sheet by means of bodies of revolution

ABSTRACT

A metal sheet is formed by passing it between a pair of closely spaced shaped bodies fixedly mounted on driving shafts by intermediate pieces which limit the angular portion of the circumferences of the shaped bodies with which the sheet comes into contact. The configuration of the surfaces of the shaped bodies define the respective top and bottom surface configurations imparted to the sheet by being passed between the rotating shaped bodies with pressure, and, optionally, heat. The direction of rotation of the shaped bodies is reversed, without the application of pressure to the sheet, to bring the sheet back to a starting position for each repeated pass of the sheet through the shaped bodies thereby to progressively change thickness and/or shape of the sheet.

BACKGROUND OF THE INVENTION

The invention relates to a method for forming a metal sheet, inparticular a plate, using bodies of revolution in which the end productscan have both variable material thicknesses and multi-axial curvatures.At the same time, the invention relates to a device by means of whichthe method can be carried out.

In the metal processing industry efforts are being made to shapecomponent parts proportionate to the loads acting upon them. Then, thethickness of material and shape are the most important parameters asidefrom the quality of material.

Thus, there are various shaping manufacturing processes. Componentparts, in particular for wind turbine generator systems or shipbuilding,often have to pass through many such processes until the end product isfinished.

First of all, die forging can be mentioned by means of which compactcomponent parts having restricted dimensions are formed, such as stubaxles, connecting rods or crankshafts. The invention according to DE 7005 237 U is an example of a plurality of die forgings.

The restricted component dimensions resulting from the forming forces tobe applied when die forging are disadvantageous. In addition,considerable forces have to be applied in order to achieve forming theworkpieces.

Workpieces are allowed to be brought into a curved shape by means ofbending presses. However, bending presses are well known in the metalprocessing industry long since. Document DE 60 2004 002 860 T2 can bementioned as an example.

Disadvantageously, only curved metal sheets can be fabricated withbending pressing. However, a change of the component thickness is notpossible.

In addition, rolling is well known. It serves to fabricate evensemi-finished products having a constant or variable metal sheetthickness. Thus, e.g. document DE 101 03 487 A1 shows a method offabrication of a large-area structure on motor vehicles as well as thelarge-area structure itself. According to the invention, a workpiece isprovided with defined, locally limited variable material cross-sectionsarranged any way through rolling. Thus, the surface of the rolls isconfigured such that certain portions of the workpiece will be submittedto deformation in a differently strong manner.

As a result, deformations in the longitudinal and transverse directionsof the plate can be sequentially carried out, and an associated changeof the material thickness can separately take place. If a workpiece isto be deformed both in the longitudinal and transverse directions of theplate, these operations have to be carried out sequentially which isdisadvantageous. Moreover, the invention according to DE 101 03 487 A1is restricted to the thin panels used in automotive engineering, whichare particularly easy to process.

In document DE 101 13 610 A1 a method of forming thick profiled,integral panels is disclosed. It is characterized in that forming isbeing performed in areas, and a three dimensional thickness profilearbitrarily both in the longitudinal and transverse directions is beingformed by defined superposition of the forming areas.

To cause a workpiece processed according to DE 101 13 610 A1 toadditionally undergo a deformation it has to be fed into a furtherprocessing operation in which undesired changes in properties of thematerial cannot be excluded. The extra cost incurred in this connectionfrom the manpower and additional space required for the second deviceand time required for the conveying of the workpiece into this deviceare also of disadvantage.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method by means of which ametal sheet can undergo complex forming in a single processing operationwherein bodies of revolution are used. Forming according to theinvention results in an end product which has different materialthicknesses over its length and width and which can be characterized byuni-axial or multi-axial curvatures running in the same or differentdirections.

Another object of the invention is to provide a device by means of whichthe aforementioned method can be carried out.

To achieve the object a method is provided wherein at least two bodiesof revolution bring a workpiece, with application pressure and, ifnecessary, additionally with heat, into the desired shape.

The method is characterized in that two shaped bodies are initiallyprovided wherein the top surface of an end product which is to becreated from the semi-finished product to be worked is imaged on the oneshaped body, and correspondingly the bottom surface of this end productis imaged on the other shaped body. The surface structure of theseshaped bodies can be formed in an extremely complex manner. The surfacestructure may reflect, for example, continuous transitions between areasof different material thicknesses of the end product, but suddendiscontinuities of material thickness can be given in the form of sharpedges as well. Moreover, along the circumference across the width of theshaped body it is possible to apply a contour which imparts the desiredcurvature to the semi-finished product in a direction transverse to theworking direction. The circumference of the shaped body is longer thanthe end product by the width of a constructional intermediate piece.Thus, it is ensured that the end product does not undergo unintentionalshaping.

The shaped bodies being formed as described will now be aligned in agiven neutral position on top of each other. Depending on thestructurally predetermined material thickness of the end product theforming process is started. The forming process itself is divided upinto forming phases. These are defined either by a fixed angle or anarea of equal material thickness being predetermined by the end product.The forming phases again are divided into one or several rotational rollpasses which prevent unwanted material movements during the formingprocess and which are admitted by a previously defined working directionof the forming pressure. If this pressure upon the semi-finished productdoes not result in the desired forming objective of this forming phaseso the operation of rotational roll pass will be repeated n times untilthe forming objective is achieved. Only then the forming operation willbe repeated in the following forming phases. If the product is finished,it can be removed from the device. However, it is also possible furthersteps to occur on the end product as desired. Thus, e.g., side-trimmingor undercut can immediately take place.

Forming depending on the temperature during cold forming,medium-temperature forming or warm forming takes place in a manner asneeded by the requirements on the end product as well. Thus, particularmaterial properties can be influenced by thermal head.

This solution of the objective according to the invention isadvantageous in that the workpieces cannot only be submitted to amulti-axial curvature but also to a complex distribution of materialthickness.

With this type of forming it is of advantage that the forming processhas a finished end product of complex shape made in one workingprocedure from an even sheet having a constant thickness. Thus, severalprocessing operations can be avoided up to the finished end product,which reduces the production time.

With respect to the device the object is achieved by the combination oftwo or more bodies of revolution which reproduce the accurate shape ofthe end product on their surfaces. By means of a synchronous drivesystem it is ensured that propulsion of the workpiece and rotary motionof the bodies of revolution are already coordinated like that, and thusthe end product can be produced with high accuracy. The device can besupplemented by further devices for side-trimming or undercut.

The invention will be described in more detail according to anembodiment. In the associated drawings

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an oblique view of the device according to the invention;

FIG. 2 shows a side view of the device according to the invention in theworking direction;

FIG. 3 shows a side view transversely to the working direction of thedevice according to the invention;

FIG. 4 shows a plan view upon the device according to the invention;

FIG. 5 shows an oblique view of the device according to the inventionhaving means for side-trimming the workpiece;

FIG. 6 shows a plan view upon a shaped body with sectional data;

FIG. 7 shows a side view of a workpiece worked with the device includingsectional data;

FIG. 8 shows views of the sections from FIG. 6;

FIG. 9 shows a plan view upon a workpiece worked with the device andhaving a varying workpiece thickness including sectional data;

FIG. 10 shows a sectional view taken along line A-A from FIG. 7;

FIG. 11 shows a sectional view taken along line B-B from FIG. 7;

FIG. 12 shows an oblique view of the workpiece worked with the device.

DETAILED DESCRIPTION OF THE INVENTION

It is common to FIG. 1 to FIG. 6 that the shaped bodies (1) and (2) areshown with a highly simplified shaping surface. However, it isconceivable that shoulders are present in the shaping surface of theshaped bodies (1) and (2) such that discontinuities in the materialthickness of the workpiece can be achieved. Moreover, non axialsymmetricshaped bodies may be disposed on the receiving shafts (3) and (4)instead of the simplifiedly illustrated shaped bodies (1) and (2). It ismerely required that the two shaped bodies (1) and (2) are adjusted toeach other such that the intended shape of the workpiece (5) will beobtained after the end of the forming process.

FIG. 1 shows an oblique view upon the device according to the invention.The main constituents of the device are bodies of revolution whichprimarily comprise shaped bodies (1) and (2), being supported onreceiving shafts (3) and (4), respectively. The first receiving shaft(3) and the second receiving shaft (4) are movable to each other suchthat between the first shaped body (1) being fixed on the firstreceiving shaft (3), and the second shaped body (2) being fixed on thesecond receiving shaft (4), a gap is developed through which theworkpiece (5) can be inserted into the device. The first shaped body (1)is configured in its shaping surface (17) such that, starting from thefront end of the constructional intermediate piece (6) around the shapedbody (1) up to the end of the constructional intermediate piece (6), thesurface (17) of this first shaped body (1) unrolled into a plane exactlycorresponds to the desired top surface of the end product which is to bemade from the workpiece (5). Likewise, the surface (17) of the secondshaped body (2) unrolled into the plane, starting from the front end ofthe second constructional intermediate piece (7) around the secondshaped body (2) up to the end of the constructional intermediate piece(7), is to exactly correspond to the desired bottom surface of the endproduct. Respective pieces (6) and (7) fasten respective shaped bodies(1) and (2) to respective shafts (3) and (4)

In a starting position, before the forming process, the constructionalintermediate pieces (6) and (7) exactly face each other. During formingthe workpiece (5) is brought to the proper thickness and shape throughthe shaped bodies (8) being rotatable around the axes of rotation (8)together with pressure and/or heating, the workpiece (5) being providedwith a curvature in at least one direction. Under certain circumstancesan end product of the proper thickness can be produced from theworkpiece (5) in one working step. Generally, the workpiece is graduallybrought to the desired thickness. To avoid displacement of metal of thesheet parallel to the axes (8) pressure is applied on the workpiece (5)only when driving takes place in the working direction (16). The bodiesof revolution must have synchronized drive systems (not illustratedherein). If additional passes (13), (14) between the rotating shapedbodies (1), (2) are required within a forming phase (12), then resettingthe workpiece into the starting position of the workpiece at the shapedbodies is carried out without applying pressure on the workpiece (5).This likewise applies to further passes (15) of the workpiece (5)between the shaped bodies (1), (2).

FIG. 2 shows the device according to the invention in a side view facingthe working direction (16). The receiving shafts (3) and (4),respectively, rotating around the axes of rotation support the shapedbodies (1) and (2), respectively. The shaping surfaces (17) located onthe shaped bodies (1) and (2) are configured such that the workpiece (5)inserted into the device obtains the desired shape. The circumference ofthe shaped bodies (1) and (2), respectively, is longer by the width ofthe respective constructional intermediate pieces (6) and (7),respectively, than the end product.

FIG. 3 also shows a side view though illustrating the device accordingto the invention from a direction transverse to the working direction(16). The second shaped body (2) is behind the first shaped body (1).Between the two shaped bodies (1) and (2) the workpiece (5) is insertedinto the device according to the invention.

In FIG. 4 the device according to the invention is further illustrated.Two shaped bodies (1) and (2) each having a different surface butcooperating with each other are coupled with receiving shafts (3) and(4). A workpiece (5) inserted in the working direction (16) leaves thedevice with desired forming, thus with different thicknesses and with arequired curvature. The plastic surfaces (17) are configured such that,if unrolled, they result in the desired top surface and bottom surface,respectively, of the end product fabricated from the workpiece (5).Constructional intermediate pieces (6) and (7), respectively, areinserted into the shaped bodies to define by their one extremity thestarting position prior to processing, and, likewise, the end of theprocessing operation by their opposite extremity. During the rotation ofthe receiving shafts (3) and (4) by means of drive systems the shapedbodies (1) and (2), respectively, which are disposed on the receivingshafts (3) and (4), respectively, have to be moved with a high precisionto ensure that the desired top surface and the desired bottom surface ofthe end product correspond with each other. As a result, synchronizeddrive systems have to be used, particularly as with several rotationalroll passes, repeated resetting to a starting point is required withoutapplying pressure to the workpiece (5).

FIG. 5 shows a view which is almost identical with FIG. 1 apart from theside-trimming devices (18) being additionally shown herein.

In FIG. 6 a shaped body can be seen. The sections indicated herecorrespond to FIG. 7 and FIG. 8. The workpiece (5) in FIG. 7 has athickness increasing over its length and is curved both in thelongitudinal and transverse directions as can be inferred from FIG. 8.

On the other hand, in FIG. 9 a workpiece (5) can be seen which has beenprocessed to produce more than a single change of thickness. As can alsobe seen in the views of FIG. 10 and FIG. 11, showing the sectionsindicated in FIG. 9, there is a wavy thickening (9) in the workingdirection as well as a wavy thickening (10) transverse to the workingdirection and centrally arranged on the workpiece. Moreover, severaldiscontinuities of material thickness in the form of edges (11) areworked into the workpiece transversely to the working direction.

From FIG. 12 it is seen that the workpiece (5) shown in FIG. 9 alsocomprises curvatures in the longitudinal direction. The shaped bodiesused for processing this workpiece (5) thus have approximately ans-shaped shaping surface (17) which comprises respective depressions andelevations to form the thickenings (9) and (10), respectively, and edges(11).

1.-13. (canceled)
 14. A method for complex forming a metal sheet,comprising in a first phase, providing two mutually spaced receivingshafts with respective shaped bodies, surfaces of the respective shapedbodies being configured to replicate a desired end product, andpositioning said shaped bodies relative to each other to receivetherebetween a metal sheet as a workpiece; in a second phase, aligningsaid shaped bodies so that they face each other in a predeterminedneutral position and inserting a leading edge of said workpiece betweenthe shaped bodies in said neutral position; in a third phase, effectinga first stage of forming by feeding the workpiece in a feeding directionbetween the shaped bodies under pressure while rotating the shapedbodies thereby to change at least one of thickness and contour of theworkpiece, removing the workpiece by releasing the pressure and rotatingthe rolls in a direction which moves the workpiece in a directionopposite the feed direction; and optionally, in a fourth phase effectingat least one further forming stage by repeating the first stage so thatthe shape and/or contour of the workpiece is changed progressively. 15.The method according to claim 14, further comprising effecting apre-forming stage before the first forming stage or a post-forming stageafter an otherwise last forming stage with substitution of at least oneof said shaped bodies with a differently configured shaped body.
 16. Themethod according to claim 14, further comprising trimming at least oneside edge of the workpiece.
 17. The method according to claim 16,further comprising forming at least one undercut on the workpiece. 18.The method according to claim 14, further comprising heating saidworkpiece while subjecting said workpiece to pressure.
 19. The methodaccording to claim 14, further comprising in each forming stage,contacting the workpiece with a same portion of the circumference ofeach of the bodies.
 20. Apparatus for complex forming a metal sheet,comprising a pair of shaped bodies fixed onto respective rotationallydriven shafts by respective intermediate pieces fixedly connecting theshaped bodies to the respective shafts, surfaces of the respectivebodies extending circumferentially between but not including theintermediate pieces and the surfaces being contoured to conform to theconfiguration of respective top and bottom surfaces of a metal sheet tobe formed by the shaped bodies, the shaped bodies facing each other withthe respective axis of rotation of each parallel to the axis of rotationof the other to receive the sheet therebetween while the shafts and,therewith the shaped bodies, are rotated in a direction to feed thesheet between the shaped bodies while pressure is applied to the sheetby the shaped bodies to contour and/or change thickness of the sheet bymeans of the contoured surfaces of the bodies, the shaped bodies havinga neutral position in which the intermediate pieces are in registry witheach other, thereby assuring that each pass of a sheet through theapparatus will match each preceding throughpass.
 21. The apparatusaccording to claim 20, further comprising at least one device fortrimming a side edge of the sheet.
 22. The apparatus according to claim20, wherein a surface of at least one of the bodies is configured toform an undercut on the sheet.